HTC Inspire 4G (Desire HD) APN Information

I have a HTC Inspire 4G (Desire HD) and was wondering if someone could tell me why when I go to Settings, Wireless & networks, Mobile networks, Access Point Names, the screen is blank? Is there a way to display the APN’ s that are on the phone? Can the phone use more than one APN?

The phone is unlocked, but not rooted, so that I can use it when I travel to various parts of the world thereby allowing me to use a local carrier. I was going to enter the APN for the carrier but was concerned because I could not see which APN the phone was currently using. I didn’t know if I had to erase the current one because the phone could only use one APN or if I could just add multiple APN’s as I moved around.